Oxygen Pressure Acid Leaching of Laterite Ore Tailing: Recycling Alkali and Preparing Heat Storage Material

During the reductive roasting of laterite ore with sodium sulfate as additive, sodium magnesium silicate and troilite are generated, this leads to high consumption of alkali and in turn environmental pollution of an alkali-rich tailing. Aiming to achieve the sustainable metallurgy by this route, oxygen pressure nitric acid leaching of laterite ore tailing was performed to recycle alkali and then heat storage material was prepared from the leached residue. The laterite ore tailing mainly consists of forsterite (Mg2SiO4), sodium magnesium silicate (Na2Mg2Si2O7), and troilite (FeS), of which 91.45% Na and 83.53% S were leached under the optimal conditions of leaching temperature of 150 degrees C and time of 60 min, HNO3 concentration of 0.16 mol L-1, and oxygen partial pressure of 0.50 MPa. The alkali can be reclaimed from the leachate after magnesium precipitation followed by evaporation and crystallization. A heat storage material with heat storage density of 243 kJ kg(-1 )can be prepared from the leached residue. A route for the value-added utilization of this alkali-rich tailing was established. [GRAPHICS] .